The instant invention relates to an improved ingot pusher furnace for heating a work load consisting of a plurality of aluminium ingots or billets prior to rolling the ingots or billets in a rolling mill.
It is well known for one to use a furnace to effect heating of aluminum ingots, as is disclosed in U.S. Pat. No. 3,620,520 to Ross et. al. for FURNACE HEATNG CONTROL SYSTEM, which is assigned to the assignee of the instant application. It is also well known to provide fans within such a heating furnace in order to circulate the heating medium within the furnance to effect better heat transfer with the ingots to be heated.
However, as the demand for aluminum has continued to increase, there has been a need for larger and larger aluminum ingots to be heated. It may be appreciated that as the linear size of the ingots increases, the volume of metal contained therein increases as a cubic function thereof, while the area across which heat is transferred to the ingot only increases as the square thereof, This leads to a problem that as the ingot becomes very large, typically thirty feet long, six feet wide, and two feet thick. the prior art methods of heating the ingots are inadequate due to the fact that the outer portions of the ingot are overheated and often have a higher temperature than the center portions thereof thereby causing nonuniformities in the subsequent rolling of the ingot.
In addition, due to these heat transfer problems, it is difficult to bring the ingots to uniform rolling temperature rapidly and efficiently within the furnace. As each ingot is loaded into the furnace a large quantity of heat escapes from the furnace through the open door. A second larger quantity of heat is absorbed by the relatively cold ingot. All of these conditions have a tendency to prevent the ingots from being uniformly heated.
What is needed, then, is an apparatus for improving the heat transfer characteristics of an aluminum homogenizing furnace or ingot pusher furnace so that the relatively large aluminum ingots in use today can be heated efficiently and uniformly.